The 1979 Gordon Conference on muscle, entitled "Ionic Channels in Muscle and Other Excitable Membranes", will stress fundamental, biophysical aspects of the functioning of ionic channels in the membranes of nerve, skeletal and cardiac muscle, and the acetylcholine stimulated channels of the neuromuscular junction. One of the major topics of the Conference will be channel gating i.e. how it is that ionic channels change their availability for ion passage as a response to a change in the applied field (or as a response to the application of Ach and other agonists at the neuromuscular junction). It is this process that underlies the generation and conduction of action potentials and other electrical signals in living cells. A second major topic will be ion translocation and channel selectivity i.e. the physical processes by which ions traverse the membrane. The reason for including studies on both nerve and muscle in this Conference is that it is now widely accepted that at these fundamental levels there are common mechanisms which apply to all preparations, differing only in quantitative detail. Historically basic advances in these questions have been pioneered by workers in nerve membrane, owing largely to the technical advantages afforded by e.g. giant axons, and then applied to skeletal and cardiac muscle membranes. Hence close communication between workers in these related areas is especially important, and this Gordon Conference will offer an opportunity to keep the dialogue vigorous.